UL 60947-4-1:2017 PDF Download

The UL 60947-4-1:2017 standard provides requirements for contactors and motor-starters used in low-voltage electrical circuits. This standard applies to equipment whose main contacts are intended to be connected to circuits with a rated voltage not exceeding 1,000 V AC or 1,500 V DC.

The standard covers various types of contactors and motor-starters, including those associated with overload and/or short-circuit protective devices, starters with separate protective devices, and those combined with their own short-circuit protective devices. It specifies the requirements for safety and performance characteristics, including operation, dielectric properties, degrees of protection, construction, and testing methods.

The standard also includes specific provisions for different types of contactors and motor-starters. For example, it covers AC and DC contactors, as well as AC motor-starters, such as direct-on-line starters, reduced voltage starters, star-delta starters, two-step auto-transformer starters, and rheostatic rotor starters. It provides guidelines for the protection of motors and associated circuits against operating overloads and the switching off of the power supply from the motor.

However, the standard has some exclusions. It does not cover DC starters, certain types of starters designed for special applications, liquid starters, semiconductor contactors, rheostatic stator starters, or auxiliary contacts of contactors and contactor relays. These are addressed in other standards.